This application relates generally to systems for dispensing liquids from an aerial vehicle, and particularly to fire suppression systems usable in connection with aerial vehicles, such as aircraft and rotorcraft.
The design and implementation of firefighting systems for use in airborne vehicles is a difficult endeavor at least because airborne vehicles, such as aircraft and rotorcraft (i.e., helicopters), have limited volume and payload capability, and because such systems are subject to rigorous government certification requirements to protect the safety of those flying on such vehicles as well as to protect people and property on the ground. Thus, airborne firefighting systems should be relatively small and lightweight, simple and safe to operate, with minimum impediments to government certification, while providing the longest possible endurance and the best possible effectiveness at a fire location.
Compressed Air Foam Systems (CAFS) are known in the firefighting industry for fighting fires from vehicles and platforms on the ground. Such systems include the use of a foaming agent that when combined or mixed with water, enhances the fire suppression capability of water alone. For example, when dispensed onto a fire, a water/foam mixture compared to water alone has the advantage of adhering to horizontal and vertical surfaces of a structure for long duration fire retardancy, acting as a surfactant thereby preventing re-ignition of the fire, in the case of a multi-story building, limiting water damage to the floors below the fire, and magnifying the fire suppression qualities of water by up to seven times.
Known CAFS systems for ground-based vehicles and firefighting platforms may include compressed air or inert gas injected into the water/foam mixture to aerate the water/foam mixture and to eject the water/foam mixture from a nozzle at relatively high velocities toward a relatively distant target. Compressed air or inert gas for this purpose is usually provided in the form of pressurized tanks or bottles or by one or more mechanical air compressors.
However, use of pressurized tanks or bottles or air compressors as a source for pressurized air can consume valuable space and energy resources on an airborne vehicle, are relatively heavy thereby reducing the payload available for consumable fluids such as water, foam, and fuel, and increase the risk of accidents due to the hazards associated with pressurized systems. In addition, pressurized tanks must be attached securely to an airframe, which may lengthen turnaround times when replacing depleted air tanks. Moreover, structural and weight limitations prevent pressurization of one or more water tanks carried aboard aircraft or rotorcraft where pressurized water tanks would otherwise be usable for propelling water or a water/foam mixture toward a distant target.
What is needed is a firefighting system configured for use in airborne vehicles, which overcomes the aforementioned limitations of existing CAFS systems.